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Does MTU apply to UDP?
UDP doesn’t know anything about MTU. UDP packets can have any size from 8 to 65535 bytes. The protocol layers below UDP either can send a packet of a specific size or will reject to send that packet with an error if too big.
What is UDP fragmentation?
Description. An attacker may execute a UDP Fragmentation attack against a target server in an attempt to consume resources such as bandwidth and CPU. IP fragmentation occurs when an IP datagram is larger than the MTU of the route the datagram has to traverse.
Does UDP allow fragmentation?
2 Answers. Any IP datagram can be fragmented if it is larger than the MTU. Whether it contains UDP, TCP, ICMP, etc. does not matter.
How are UDP datagrams frame the data?
UDP datagrams frame the data. Each send call generates a datagram (but see below about corking). The other side receives a full datagram (and, in the socket API, it must specify a buffer large enough to hold it, or else the datagram will be truncated).
Is there a minimum MTU size for TCP?
This is because TCP stack will not send such small segments: there is a minimum MTU size. However, if the send is anywhere in the middle of a stream, all bets are off. It could be that your protocol stack takes 10 byte of the data to fill a segment and send it out, and then then next ten bytes go to another segment.
How does a protocol stack break data into chunks?
Your protocol stack breaks data into chunks and places them into a queue. The chunk sizes are based on the path MTU. If you perform a send operation, and there is still queued data pending, the protocol stack will typically peek at the segment which is at the tail of the queue and see whether there is room in that segment to add more data.
What happens when two UDP packets are split?
If a datagram gets split over two packets, the IP protocol will reassemble it for the UDP protocol, so you will see the complete data. You can’t be sure that they really physically arrive at once. The Data link layers below TCP/UDP might split your packet up if they want to.